TQ2440移植u-boot2016.11-NAND FLASH方式啓動U-BOOT
S3C2440 U-BOOT啓動方式說明:
NOR FLASH啓動: S3C2440會直接在NOR上運行程序,在NOR上中的代碼需要初始化芯片時鐘、初始化SDRAM。
NAND FLASH啓動: S3C2440上電後其內部的NAND FLASH控制器會自動把NAND FLASH中的前4K的代碼拷貝到S3C2440芯片自帶的RAM中,然後開始運行程序,因爲片上RAM只有4K的容量,所以這部分的代碼就負責初始化芯片時鐘、初始化SDRAM、初始化NAND,然後將u-boot的代碼拷貝到SDRAM中並跳轉運行。
目前主流的啓動方式爲NAND FLAHS或者SD卡啓動,NOR FLASH用的越來越少了,上二章節已經實現了NOR FLASH的啓動,本章節實現NAND FLASH的啓動。
u-boot在編譯時候開啓了-pie選項,該選項的作用是編譯出來的程序是位置無關的,什麼意思呢,就像是動態庫庫一樣,代碼每次啓動可以自由加載到內存的任意合適位置執行。如果我們開啓了該功能,那麼NAND前4K的代碼中有一些變量等代碼就可能不在這4K中,而是在一些特殊的段或者位置處,這樣的話S3C2440上電自動拷貝NAND前4K的內容並運行就會出錯,解決該辦法的方式有兩種:
- 修改u-boot執行的主流程,取消掉uboot重定位,在4K代碼中實現複製代碼到內存的操作。
- 設置爲SPL啓動,SPL啓動簡單的說就是編譯u-boot的時候會生成u-boot.bin和u-boot-spl.bin文件,通過宏
CONFIG_SPL_BUILD
控制是編譯u-boot.bin還是u-boot-spl.bin,spl代碼只是對時鐘的初始化、SDRAM初始化、NAND初始化並將u-boot從NAND中拷貝到內存並跳轉運行的操作,所以這段代碼肯定是小於4K的。
本例程使用SPL方式進行引導uboot。
(一)修改配置頭文件:
gedit include/configs/tq2440.h
1、由於SPL的代碼已經初始化了內存,所以SPL將uboot拷貝到內存並運行後,不需要再次初始化內存了,將宏CONFIG_SKIP_LOWLEVEL_INIT
的編譯條件由CONFIG_SPL_BUILD
控制,改爲如下代碼:
/* 該宏是在文件arch/arm/cpu/arm920t/start.S中跳過SDRAM初始化代碼 */
#ifndef CONFIG_SPL_BUILD
#define CONFIG_SKIP_LOWLEVEL_INIT
#endif
2、修改鏈接地址也由宏CONFIG_SPL_BUILD
控制,如果是SPL那麼鏈接到0地址處,如果是uboot那麼鏈接到內存0x30008000地址處,將宏CONFIG_SYS_TEXT_BASE
改爲:
#ifdef CONFIG_SPL_BUILD
#define CONFIG_SYS_TEXT_BASE 0
#else
#define CONFIG_SYS_TEXT_BASE 0x30008000
#endif
(二)添加SPL編譯項
gedit arch/arm/Kconfig
找到config TARGET_TQ2440
的配置項,在該配置項結尾加入一行:select SUPPORT_SPL
,效果:
(三)添加拷貝u-boot到內存的代碼
新建一個init.c文件:
gedit board/samsung/tq2440/init.c
粘貼進如下代碼:
/*
* init.c
*
* Created on: 2020/03/28
* Author: AnKun
*/
#define NFCONF (*(volatile unsigned int *)0x4E000000)
#define NFCONT (*(volatile unsigned int *)0x4E000004)
#define NFCMD (*(volatile unsigned char *)0x4E000008)
#define NFADDR (*(volatile unsigned char *)0x4E00000C)
#define NFDATA (*(volatile unsigned char *)0x4E000010)
#define NFSTAT (*(volatile unsigned char *)0x4E000020)
#define GPBCON (*(volatile unsigned int *)0x56000010)
#define GPBDAT (*(volatile unsigned int *)0x56000014)
#define GPBUP (*(volatile unsigned int *)0x56000018)
#define tq2440_nand_select() do{NFCONT &= ~(1 << 1);}while(0);
#define tq2440_nand_deselect() do{NFCONT |= 1 << 1;}while(0);
static int is_boot_from_nor_flash(void)
{
int tmp = 0;
volatile int* p = (volatile int *)0;
tmp = *p;
*p = 0xAAAAAAAA;
if (*p == 0xAAAAAAAA) /* boot from nand */
{
*p = tmp;
return 0;
}
else /* boot from nor */
{
return 1;
}
}
void tq2440_nand_init(void)
{
#define TACLS 0
#define TWRPH0 1
#define TWRPH1 0
NFCONF = (TACLS << 12) | (TWRPH0 << 8) | (TWRPH1 << 4);
NFCONT = (1 << 4) | (1 << 1) | (1 << 0);
}
void tq2440_nand_delay(void)
{
int delay = 0;
for (delay = 0; delay < 10; delay++);
}
void tq2440_nand_write_cmd(unsigned char cmd)
{
NFCMD = cmd;
tq2440_nand_delay();
}
void tq2440_nand_write_addr(unsigned int addr)
{
unsigned int col = addr % 2048;
unsigned int page = addr / 2048;
NFADDR = col & 0xFF;
tq2440_nand_delay();
NFADDR = (col >> 8) & 0xFF;
tq2440_nand_delay();
NFADDR = page & 0xFF;
tq2440_nand_delay();
NFADDR = (page >> 8) & 0xFF;
tq2440_nand_delay();
NFADDR = (page >> 16) & 0xFF;
tq2440_nand_delay();
}
void tq2440_nand_wait_ready(void)
{
while (!(NFSTAT & 0x1)) {};
}
void tq2440_nand_read(unsigned int addr, void* buf, unsigned int len)
{
int i = 0;
int col = addr % 2048;
unsigned char* p = (unsigned char *)buf;
tq2440_nand_select();
while (i < len)
{
tq2440_nand_write_cmd(0x00);
tq2440_nand_write_addr(addr);
tq2440_nand_write_cmd(0x30);
tq2440_nand_wait_ready();
for (; (col < 2048) && (i < len); col++)
{
*p++ = (NFDATA & 0xFF);
i++;
addr++;
}
col = 0;
}
tq2440_nand_deselect();
}
int mymemcmp(const void* addr1, const void* addr2, unsigned int len)
{
char* p1 = (char *)addr1;
char* p2 = (char *)addr2;
while (len--)
{
if (*p1 != *p2)
return 1;
p1++;
p2++;
}
return 0;
}
#define TQ2440_UBOOT_COPYTO 0x30008000 /* 拷貝到內存中的地址,此值與CONFIG_SYS_TEXT_BASE一致 */
#define TQ2440_UBOOT_OFFSET 0x20000 /* u-boot在NAND中的偏移地址(NAND中的前128K存放的是u-boot-spl.bin) */
#define TQ2440_UBOOT_SIZE 0xE0000 /* u-boot的大小896K,多拷貝點沒關係 */
void copy_uboot_to_sdram(void)
{
void (*jump)(void) = (void *)TQ2440_UBOOT_COPYTO;
GPBDAT &= ~(1 << 5);
if (is_boot_from_nor_flash())
{
int len = TQ2440_UBOOT_SIZE;
char* s = (char *)TQ2440_UBOOT_OFFSET;
char* d = (char *)TQ2440_UBOOT_COPYTO;
GPBDAT &= ~(1 << 6);
while (len--) *d++ = *s++;
GPBDAT &= ~(1 << 7);
GPBDAT &= ~(1 << 8);
}
else
{
tq2440_nand_init();
GPBDAT &= ~(1 << 6);
tq2440_nand_read(TQ2440_UBOOT_OFFSET, (void *)TQ2440_UBOOT_COPYTO, TQ2440_UBOOT_SIZE);
GPBDAT &= ~(1 << 7);
GPBDAT &= ~(1 << 8);
}
jump();
}
void tq2440_led_init(void)
{
GPBCON = 0x002956A9;
GPBUP = 0x000007FF;
GPBDAT = 0x000001E0; /* led off */
}
void clsbss(void)
{
extern int __bss_start;
extern int __bss_end;
int* p = &__bss_start;
while (p < &__bss_end) *p++ = 0;
}
void tq2440_board_init_f(void)
{
clsbss();
tq2440_led_init();
copy_uboot_to_sdram();
}
(四)修改彙編啓動文件crt0.S:
gedit arch/arm/lib/crt0.S
找到:
mov r0, #0
bl board_init_f
替換爲:
#ifndef CONFIG_SPL_BUILD
mov r0, #0
bl board_init_f
#else
bl tq2440_board_init_f
#endif
(五)將init.c添加進編譯項:
gedit board/samsung/tq2440/Makefile
添加一行:
obj-$(CONFIG_SPL_BUILD) += init.o
(六)編譯
1、首先make一下編譯出u-boot.bin
2、然後打開SPL的編譯項:
make menuconfig ---> SPL / TPL ---> 選中
保存退出後,make一下,在spl目錄下就編譯出了u-boot-spl.bin文件。
將u-boot-spl.bin燒寫到NAND中的0地址處,將u-boot.bin燒寫到NAND的128K地址處,TQ2440開發板撥到NAND啓動,重新上電即可成功啓動。
注意:NAND啓動無法識別NOR FLASH,此處問題先保留,回頭解決。
【附加】:分別燒寫u-boot-spl.bin和u-boot.bin很麻煩,所以我寫了個小程序將這兩個文件合併爲一個文件。新建文件ubootmeger.c
文件,粘貼進如下代碼:
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
uint8_t buffer[0x200000];
#define UBOOT_SPL_SIZE (128*1024)
int main(int argc, char* argv[])
{
int nread = 0;
int nwrite = 0;
FILE* fp1;
FILE* fp2;
FILE* fp3;
if(argc < 3)
{
printf("\r\nUsage:\r\n\tubootmerge [u-boot-spl.bin] [u-boot.bin] [output filename]\r\n");
printf("e.g.\r\n\tubootmerge u-boot-spl.bin u-boot.bin tq2440-uboot-2016.11.bin\r\n");
return 0;
}
fp1 = fopen(argv[1], "rb");
fp2 = fopen(argv[2], "rb");
fp3 = fopen(argv[3], "wb+");
if(!fp1 || !fp2 || !fp1)
{
fprintf(stderr, "Can not open file, please again!\r\n");
goto __exit;
}
memset(buffer, 0xFF, sizeof(buffer));
nread = fread(buffer, 1, UBOOT_SPL_SIZE, fp1);
if(nread < 0)
{
fprintf(stderr, "Can not read file %s, please again!\r\n", argv[1]);
goto __exit;
}
nwrite += UBOOT_SPL_SIZE;
nread = fread(buffer + nwrite, 1, 0x100000, fp2);
if(nread < 0)
{
fprintf(stderr, "Can not read file %s, please again!\r\n", argv[2]);
goto __exit;
}
nwrite += nread;
if(fwrite(buffer, 1, nwrite, fp3) != nwrite)
{
fprintf(stderr, "Can not write file %s, please again!\r\n", argv[3]);
goto __exit;
}
printf("---==> done !\r\n");
goto __exit;
__exit:
fclose(fp1);
fclose(fp2);
fclose(fp3);
return 0;
}
使用gcc編譯一下即可:
gcc -o ubootmeger ubootmeger.c
使用方法:ubootmeger
接收三個參數,第一個參數爲spl文件名,第二個參數爲uboot的文件名,第三個參數爲合併新uboot的文件名,例:
./ubootmeger u-boot-spl.bin u-boot.bin tq2440-u-boot-v201611.bin
文件tq2440-u-boot-v201611.bin
即爲最終版的u-boot,將該u-boot燒寫進nor或者nand中0地址處即可。
ends…